This project will study the optimization of speeded decisions, and the control and monitoring mechanisms that serve this optimization by balancing performance costs and benefits. These lines of work will be pursued under two specific aims. First, we will build on theoretical work from the previous period, which used the drift diffusion model and neural network modeling to produce detailed predictions about behavior and the dynamics of neural mechanisms underlying control. Here, we aim to test these predictions using behavioral, fMRI, and electrophysiological techniques, in coordination with continued modeling and analysis work in Project 6. These studies will address two-alternative forced choice tasks in which speeded decisions must be made between a correct (rewarded) and incorrect (unrewarded) alternative, tasks that will also be explored within human developmental and non-human primate populations in Projects 2, 4, and 5. In a second, complementary line of work, we will extend our investigation to decisions that require a more graded evaluation of the relative costs and benefits of alternative courses of action. Many decisions do not involve a simple choice between correct vs. incorrect (rewarded vs. unrewarded) alternatives, but rather require an evaluation of the relative costs and benefits of the options. We will use behavioral, imaging, electrophysiological, and pupillometric methods to characterize the neural mechanisms involved in evaluating costs and benefits in such circumstances, and how these evaluations are combined to compute utility and control decision making within and between tasks. Experiments in this second line of studies will parallel developmental studies in Project 4 and neurophysiological studies in Project 5 examining the decision between a well-defined alternative versus the opportunity to explore other alternatives.